Growing Lettuce in the Tokyo Underground Isn't So Different From Growing it in Space

A project by the company that runs the city’s underground trains, Tokyo Metro, has been highlighted by Naomi Gingold of PRI, who visited one of the hydroponic farms. Between stations on the blue Tozai line, the company is growing several types of greens and selling them to a nearby restaurant and hotel, though it hopes to sell salads and smoothies directly to commuters eventually, says Gingold.

The project is headed up by the company’s director of new business, who has been growing under the Tozai line since January, according to the train company’s own press release. It’s a clever play on both emerging farming technology and the public’s understandably anxiety about the provenance and safety of their produce after Fukushima.

If you’re not familiar with the technology, here’s a great primer by Gizmodo’s own Maddie Stone. There are many types of hydroponic and aeroponic systems, but most of these work without soil by delivering nutrient-rich water to plants’ roots, instead. The plants either get spritzed with a mist (in aeroponic systems) or float in this solution so their roots have steady access to the important nutrients they usually get from dirt, like potassium and zinc. Sometimes, a nutrient-rich clay or fertiliser is used.

What about light? That comes from a combination of carefully chosen coloured LEDs or fluorescent lights that provide the wavelengths the plants need to thrive. Since the farms are carefully controlled and don’t contain all the trappings of, you know, nature, there are no insects (or human-made chemicals!) to wash off the produce when it’s harvested, which is definitely an attractive proposition for consumers.

How is any of this different from the historic event we witnessed earlier this week, when astronauts aboard the ISS ate the first lettuce grown in space? NASA’s seeds grow in pillows of a clay called arcillite, and fertiliser. The so-called Veggie system (yes, that’s the official name) is geared towards the cramped conditions and weight-sensitive rocket launches, and arrives on the ISS packed in “pillows” that are watered aeroponically at the bottom of expandable accordion-style growing cages topped by LEDs that provided the red, green, and blue light that the produce needed.

Space greens! Image: NASA

So in the end, the way we grow veggies in space isn’t very different from the way we grow them in unusual places here on Earth; indeed, these experiments have paved the way for the ISS’s recent harvest. It’s easy to imagine a future in which emerging soil-less farming technology is less of a novelty and more a lifeline on a changing planet but for now, they remain in development in some of the least hospitable parts of our world: in our infrastructure, and orbiting in space. [PRI h/t Archinect; Image of the Tokyo Metro Fukutoshin Line Shibuya Station by Naoya Fujii]